Several experienced cyclists have complained to me about the need to frequently urinate during races.
These cyclists, both roadies and mountain bikers, notice the issue during long events (those over three hours). The athletes are all highly trained, practicing the same nutrition and hydration techniques in training that they play to use on race day. The athletes tell me they don't think they feel particularly nervous on race day.
For the athletes that race at altitude, all of them are acclimatized and do not experience the problem during training rides.
It has taken me awhile to troubleshoot this problem and eliminate several possibilities, but I have a theory about what is going on. Let me share it with you.
Root Cause of the Problem
For the cyclists I coach, and those that have written to me describing this problem, I believe the root cause is some combination of these issues:
- Pre-race nerves
- Cold race start temperatures
- Waiting in a pre-race queue for 30 minutes or more
- Light clothing worn at the cool race start, in preparation for higher temperatures anticipated later in the event
- The athlete feels cold and in some cases, is shivering at race start
- For those racing unacclimatized at altitude, the problem is exacerbated
The Body's Response to Stress
There are different types of stress placed on our bodies when we race. In his book Performing in Extreme Environments, Dr. Lawerence E. Armstrong notes that the body can adequately acclimatize to heat, cold and altitude stress with about eight to 14 days of exposure. Loss of this acclimatization occurs in some after 14 to 28 days.
As with many physiological issues, there are individual variances in how a body responds to environmental and mental stress. Some of the differences are related to genetics, level of physical fitness, immune system, competence, age, previous experience with similar stress and mental skills.
Interestingly, several environmental stressors and some physical stressors, such as sleep deprivation, can be mediated by psychological factors. For some racers, the stressors are not viewed as noxious or alarming, so these racers produce small or even opposite physiological responses compared to others in the same situation.
In other cases, stressed athletes feel the need to void when they get stressed. This can be exacerbated by a dry-mouth feeling, causing the athlete to drink more fluid than normal. It is further exacerbated by those racing unacclimatized to altitude, as altitude also increases urination.
The Body's Response to Cold
Your body does its very best to keep core body temperature at 37 degrees Celsius (98.6 degrees Fahrenheit). When exposed to cold environments, the body takes action by engaging changes in the nervous, endocrine, cardiovascular, muscular and urinary systems. The body's approach is three-pronged: increase heat production (shivering), reduce heat loss (constrict blood vessels) and mobilize metabolic fuels (release free fatty acids and glucose).
One of the unfortunate responses to the reduction of peripheral blood flow (meant to maintain core body temperature) is an increase in urine volume during cold exposure.